1. Field of the Invention
The present invention relates to a cleaning apparatus for cleaning a semiconductor wafer, and more particularly to a cleaning apparatus for cleaning a semiconductor wafer that needs to have a high degree of cleanness.
2. Description of the Related Art:
As semiconductor devices have become more highly integrated in recent years, circuit interconnections on semiconductor substrates become finer and distances between such circuit interconnections become smaller. When semiconductor wafers are processed, fine particles such as particles of semiconductor material, dust particles, crystalline protrusive particles, or the like often tend to be attached to the semiconductor wafers being processed. If a particle greater in size than the distance between interconnections exists on a semiconductor substrate, then the particle will short-circuit interconnections on the semiconductor substrate. Therefore, any undesirable particles on a semiconductor substrate have to be sufficiently smaller than the distance between interconnections on the semiconductor substrate. Such a problem and a requirement hold true for the processing of other substrates including a glass substrate to be used as a mask, a liquid crystal panel, and so on. To meet the above requirement, there have been practiced various cleaning procedures for removing fine particles or submicron particles from semiconductor wafers.
For example, as a cleaning method for cleaning a semiconductor wafer which has been polished, there has heretofore been one practice to use a brush of nylon, mohair or the like, or a sponge of polyvinyl alcohol (PVA) to scrub a surface of a semiconductor wafer. This process is called a scrubbing cleaning process. Further, there have been other practices, one of which is an ultrasonic cleaning process in which water having ultrasonic vibrational energy applied thereto is supplied to a surface of a semiconductor wafer, the other of which is a cavitation jet cleaning process in which high pressure water generating cavitation is supplied to a surface of a semiconductor wafer. Also, a cleaning process which combines two or three of the above processes is known in the art. In addition, a cleaning process may be combined with a spin drying process in which a cleaned semiconductor wafer is rotated at a high speed to remove under centrifugal forces any cleaning liquid such as water that has remained on the surface of the semiconductor wafer from the cleaning process.
The above conventional cleaning apparatuses which are designed to carry out the above scrubbing process or any other cleaning process combined with the spin drying process do not have a mechanism for detecting a reference position on a semiconductor wafer, which may be represented by an orientation flat or a notch, and stopping the semiconductor wafer at a predetermined position. Therefore, if a need arises for aligning the reference position on a semiconductor wafer with a certain direction after the semiconductor wafer has been cleaned, then an additional device for achieving such positional alignment of the semiconductor wafer is required.
Further, the conventional cleaning apparatuses do not directly detect the rotational speed of a semiconductor wafer upon rotation thereof, but indirectly detect it by detecting the rotational speed of a drive power source or a drive shaft by which the semiconductor wafer is rotated. Consequently, the conventional cleaning apparatuses fail to detect a rotation failure or a rotation abnormality of the semiconductor wafer which is caused by wear or other troubles of a component of a power transmitting mechanism which is interposed between the drive power source and the semiconductor wafer.
It is therefore an object of the present invention to provide a cleaning apparatus for carrying out a scrubbing process, a spin drying process, or the like which has a sensor for detecting a reference position on a semiconductor wafer, which may be represented by an orientation flat or a notch, and a function for stopping the semiconductor wafer whose reference position is aligned with a given direction and/or a function for directly detecting the rotational speed of the semiconductor wafer.
In order to achieve the above object, according to one aspect of the present invention, there is provided an apparatus for performing at least one of cleaning and drying a semiconductor wafer while rotating the semiconductor wafer, comprising: a rotating mechanism for rotating the semiconductor wafer; a sensor for detecting a reference position of the semiconductor wafer.
According to another aspect of the present invention, there is also provided a polishing apparatus for polishing a semiconductor wafer, comprising: a polishing section for polishing a surface of the semiconductor wafer; and a cleaning apparatus for cleaning the polished surface of the semiconductor wafer, the cleaning apparatus comprising: a rotating mechanism for rotating the semiconductor wafer; and a sensor for detecting a reference position of the semiconductor wafer.
According to the present invention, based on the detection of the reference position of the semiconductor wafer during rotation of the semiconductor wafer, it is possible to detect the rotational speed of the semiconductor, and to stop the semiconductor wafer from rotating to align the reference position with a predetermined position.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.